This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-275290, filed Sep. 11, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a process unit, an image formation device provided with the same, and a color image formation device with the same.
2. Description of the Related Art
An image formation device using an electrophotographic method which has a conveyor for conveying a sheet of recording paper and an image formation mechanism for forming a desired image on a sheet of the recording paper being conveyed by the conveyor using an electrophotographic method is well known and is widely used as what is called a copying machine or a printer. The above-described image formation mechanism essentially includes a rotating photosensitive drum, a charger for charging an outer peripheral surface of this photosensitive drum, an exposure device for forming a desired electrostatic latent image on the charged outer peripheral surface, a developing device for developing the electrostatic latent image on the outer peripheral surface of the photosensitive drum by toner to form a toner image, a transfer device for transferring the toner image formed on the outer peripheral surface of the photosensitive drum to a sheet of the recording paper conveyed by the conveyor and a cleaner for removing toner remaining on the outer peripheral surface of the photosensitive drum after transferring a toner image from the outer peripheral surface of the photosensitive drum to a sheet of the recording paper being conveyed.
In the case where the developing device uses a developing roller, the developing roller is disposed with respect to the photosensitive drum so that the respective rotation center lines of the developing roller and the photosensitive drum are parallel with each other and both of them are directed in the same direction. Then, between the mutual adjacent portions of the outer peripheral surface of the developing device and the outer peripheral surface of the photosensitive drum, for example, a space and contact depth having the predetermined dimensions is provided according to image formation conditions such as, for example, a kind of toner, an image formation speed (developing speed) and the like. The predetermined dimensions of the space and the contact depth are values by which the best image quality is obtained according to the image formation conditions.
In the above-described kind of image formation device in prior art, one independent process unit is constituted by combining a photosensitive drum and a developing device together. In a greater detail, the rotation center axis of the photosensitive drum is supported in a freely rotatable manner by the photosensitive drum frame and the photosensitive drum section is constituted by the photosensitive drum frame with the photosensitive drum. Moreover, the rotation center axis of the developing roller of the developing device is supported in a freely rotatable manner by a developing roller frame, and the developing device section is constituted by the developing roller frame with the developing device including the developing roller. Then, photosensitive drum frame and the developing roller frame are combined so that the mutual distance between the photosensitive drum frame and the developing roller is changeable.
In the photosensitive drum frame and the developing roller frame which are combined with each other, the positions of the photosensitive drum and the developing roller are adjusted so as to be in a state where the respective rotation center lines are parallel to each other and directed in the same direction.
Then, before such a process unit is incorporated into the image formation device, the distance is set and fixed in the process unit according to the image formation conditions required in its image formation device.
In manufacturing of the conventional process unit, the setting work for the distance is troublesome. Therefore, after the distance has been set at a predetermined value and fixed, the work for changing it to another value has also been troublesome.
Therefore, in manufacturing of the conventional process unit, after the above distance in the process unit has been set and fixed according to the image formation conditions required in the image formation device in which the process unit is incorporated, it has been hardly ever carried out that the distance was changed to another value.
Therefore, when a rapid demand variation among a variety of image information devices has occurred, it has been difficult to apply a process unit for another image formation device having a large stock to the image formation device whose demand is rapidly increased. As a result it has been difficult to deal with the rapid increase of a demand for one device, and it has also been difficult to reduce the stock of the process unit for the other image formation device having a large stock.
The present invention has been achieved under the circumstances, and an object of the present invention is to provide a process unit capable of easily and rapidly performing the change of the mutual distance between the photosensitive drum and the developing roller for various kinds of image formation devices having different image formation conditions.
A further object of the present invention is to provide an image formation device and a similar color image formation device whose economical values are enhanced by being provided with such a process unit.
In order to achieve the object of the present invention as described above, a process unit according to the present invention comprises:
a photosensitive drum section including a photosensitive drum having a rotation center axis and an outer peripheral surface, and a photosensitive drum frame for supporting the rotation center axis of the photosensitive drum in a rotatable manner;
a developing device section which includes a developing roller having a rotation center axis and an outer peripheral surface, and a developing roller frame for supporting a rotation center axis of the developing roller in a rotatable manner, in which the developing roller frame and the photosensitive drum frame are coupled so that the mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum is set in an adjustable manner as well as these are disposed so that the rotation center axis of the developing roller is parallel with the rotation center axis of the photosensitive drum from each other and directed in the same direction with respect to the rotation center axis of the photosensitive drum in a state where the developing roller is made located adjacent to the photosensitive drum; and
an inter-axis distance regulation mechanism which is provided in either of the photosensitive drum frame of the photosensitive drum section and the developing roller frame of the developing device section in a movable manner by which the inter-axis distance regulation mechanism is movable between multiple stages, which is in contact with the predetermined other position of the photosensitive drum and the developing roller frame and which can adjust a mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum in multiple stages by its moving to the one of them in multiple stages.
In order to achieve the object of the present invention as described above, an image formation device according to the present invention comprises:
a conveyor for conveying a sheet of recording paper;
a photosensitive drum section including a photosensitive drum having a rotation center axis and an outer peripheral surface and a photosensitive drum frame for supporting the rotation center axis of the photosensitive drum in a rotatable manner;
a charger for charging the outer peripheral surface of the photosensitive drum,
an exposure device for forming a desired electrostatic latent image on the charged outer peripheral surface of the photosensitive drum;
a developing device section which includes a developing roller having a rotation center axis and an outer peripheral surface and a developing roller frame for supporting a rotation center axis of the developing roller in a rotatable manner, in which the developing roller frame and the photosensitive drum frame are coupled so that a mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum in an adjustable manner as well as these are disposed so that the rotation center axis of the developing roller is in parallel to the rotation center axis of the photosensitive drum and is directed in the same direction with respect to the rotation center axis of the photosensitive drum in a state where the developing roller is made located adjacent to the photosensitive drum and which develops an electrostatic latent image on the outer peripheral surface of the photosensitive drum using toner by the developing roller and forms a toner image;
an inter-axis distance regulation mechanism which is provided in either of the photosensitive drum frame of the photosensitive drum section and the developing roller frame of the developing device section in a movable manner by which the inter-axis distance regulation mechanism is movable between multiple stages, which is in contact with the predetermined other position of the photosensitive drum and the developing roller frame and which can adjust the mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum in multiple stages by its moving to the one of them in multiple stages;
a transfer device for transferring the toner image formed on the outer peripheral surface of the photosensitive drum to a sheet of the recording paper being conveyed by the conveyor; and
a cleaner for removing toner remaining on the outer peripheral surface of the photosensitive drum after transferring a toner image from the outer peripheral surface of the photosensitive drum to a sheet of the recording paper being conveyed.
In order to achieve the object of the present invention as described above, a color image formation device according to the present invention comprises:
a conveyor for conveying a sheet of recording paper; and
image formation units which are disposed in multiple number of positions along a conveyance path of a sheet of the recording paper being conveyed by the conveyor and which form a desired color image on a sheet of the recording paper being conveyed by the conveyor, respectively,
each of the multiple image formation units is provided with,
a photosensitive drum section including a photosensitive drum having a rotation center axis and an outer peripheral surface, and a photosensitive drum frame for supporting the rotation center axis of the photosensitive drum in a rotatable manner;
a charger for charging the outer peripheral surface of the photosensitive drum,
an exposure device for forming a desired electrostatic latent image on the charged outer peripheral surface of the photosensitive drum;
a developing device section which includes a developing roller having a rotation center axis and an outer peripheral surface and a developing roller frame for supporting a rotation center axis of the developing roller in a rotatable manner, in which the developing roller frame and the photosensitive drum frame are coupled so that a mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum in an adjustable manner as well as which is disposed so that the rotation center axis of the developing roller is in parallel to the rotation center axis of the photosensitive drum and is directed in the same direction with the rotation center axis of the photosensitive drum in a state where the developing roller is made located adjacent to the photosensitive drum and which develops an electrostatic latent image on the outer peripheral surface of the photosensitive drum using the desired color toner by the developing roller and forms the desired color toner image;
an inter-axis distance regulation mechanism which is provided in either of the photosensitive drum frame of the photosensitive drum section and the developing roller frame of the developing device section in a movable manner by which the inter-axis distance regulation mechanism can be movable between multiple stages, which is in contact with the predetermined other position of the photosensitive drum frame and the developing roller frame and which can adjusts the mutual distance between the outer peripheral surface of the developing roller and the outer peripheral surface of the photosensitive drum in multiple stages by its moving to the one of them in multiple stages;
a transfer device for transferring the desired color toner image formed on the outer peripheral surface of the photosensitive drum to the sheet of the recording paper being conveyed by the conveyor; and
a cleaner for removing the desired color toner remaining on the outer peripheral surface of the photosensitive drum after transferring the desired color toner image from the outer peripheral surface of the photosensitive drum to the sheet of the recording paper being conveyed.